Roofing shingles have long been used to provide protection for housing structures. Laminated, or multi-layered, shingles are commonly used in roofing applications due to the increased protection and improved aesthetics provided by such shingles.
Multi-layered shingles utilize various forms of adhesive to interconnect the individual layers of the shingle. It has been discovered that, over time, the adhesive used in connecting the layers may weaken, or fail, which can prove detrimental to the roofing structure. For example, failed adhesive can cause individual shingle layers to slide, or slump, relative to one another, thereby resulting in an aesthetically displeasing appearance of the roofing structure. In more extreme cases, slumping can lead to overall failure of the roofing structure. Such problems are particularly relevant in roofing structures disposed in warm climates and/or those roofing structures having a steep pitch.
The above-described slump problem often arises when multi-layered shingles are installed incorrectly. Multi-layered shingles typically include layers of varying size. For example, a top layer of the shingle may have a larger area than a bottom layer of the shingle. Accordingly, methods for installation generally instruct that shingles should be nailed to a roofing structure by driving a nail through the multi-layered portion of the shingle, also referred to as the “common bond” or the “nail zone” portion of the shingle. However, in practice, multi-layered shingles are often incorrectly secured to roofing structures by nailing outside of the common bond. Incorrect installation can occur for a number of reasons, including insufficient instructions, communication barriers, or plain incompetence.
Slump has heretofore been addressed by increasing the size of the common bond and/or applying supplemental or modified adhesives to strengthen the connection between layers of multi-layered shingles. While providing improved performance, these approaches are ultimately limited by the physical and chemical properties associated with the composition of the shingles and the adhesives used in connecting the shingles. Thus, rather than solve the problem of slump, these approaches merely delay the appearance of slump. Moreover, increasing the size of the common bond often entails increasing the size of at least one of the layers, which has proven to be quite costly.
Accordingly, an enhanced multi-layered shingle is desired that eliminates the slump problems associated with conventional multi-layered shingles.